Page 733 - Small Animal Clinical Nutrition 5th Edition

760 Small Animal Clinical Nutrition

VetBooks.ir CASE 36-2

Dilated Cardiomyopathy in an American Cocker Spaniel Dog
Bruce W. Keene, DVM, Dipl. ACVIM (Cardiology)
College of Veterinary Medicine
North Carolina State University
Raleigh, North Carolina, USA

Patient Assessment
A nine-year-old, male black American cocker spaniel dog was examined for dyspnea and lethargy that began two days after a rou-
tine elective surgical procedure (removal of a subcutaneous mass).The dog was thin (body condition score 2/5) and weighed 12 kg.
Vaccinations were current and the dog received heartworm preventive medication.The dog had not had any major health problems
in the past.
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The heart rate was 180 beats/min. and regular, the respiratory rate 76 breaths/min. and the rectal temperature 39.9 C (103.8 F).
The mucous membranes were dusky pink, with slow capillary refill. A soft (1/6 to 2/6) holosystolic murmur was heard best at the
left cardiac apex, accompanied by a diastolic gallop sound (felt to be S3). The lung sounds were loud with some inspiratory crack-
les heard bilaterally. Otitis externa was noted bilaterally. An incision behind the right shoulder oozed slightly on palpation.
Thoracic radiographs revealed generalized, severe cardiomegaly with alveolar pulmonary edema (Figures 1A and 1B). An
echocardiogram revealed a left ventricular diameter of 5.68 cm in diastole (extremely dilated), with only an 8% shortening fraction
(normal = 30 to 45%), but no major structural lesions were found on any valves (Figure 2). The echocardiographic findings were
consistent with a diagnosis of dilated cardiomyopathy.
Results of an arterial blood gas analysis revealed hypoxemia and hyperventilation (PaO = 71 mm Hg [reference range = 92.1 ±
2
5.6], pH = 7.4 [7.4], PaCO = 30.8 mm Hg [36.8 ± 3.0]). Results of a complete blood count included normal red cell indices
2
(packed cell volume = 39% [reference range = 38 to 57]), with an elevated leukocyte count (23,900/µl [reference range = 6.1 to 17.4])
consisting of a neutrophilia with a left shift (2,868 bands/µl [reference range = 0 to 300]). The platelet count was normal. Results
of a serum biochemistry profile (including albumin, creatinine, urea nitrogen, electrolytes and liver enzymes) were within normal
limits. Urinalysis disclosed an inactive sediment with a urine specific gravity of 1.024 (reference range = 1.001 to 1.070). The tau-
rine concentration in a sample of whole blood was decreased (28.6 µmol/l; normal = 40.0 to 120.0), as was the plasma concentra-
tion of L-carnitine (plasma free carnitine 4.2 µmol/l; normal = 8.0 to 36.0).

Assess the Food and Feeding Method
The dog was fed a variety of dry commercial dog foods, free choice.

Questions
1. What is the feeding plan for this patient?
2. Should this dog be given nutritional supplementation?

Answers and Discussion
1. General nutritional recommendations for patients with cardiac disease and congestive heart failure (CHF) include the following:
avoid excess sodium and chloride; ensure adequate magnesium intake; ensure adequate potassium intake, if using diuretics; avoid
excess potassium intake, if using angiotensin-converting enzyme (ACE) inhibitor drugs; ensure adequate energy and protein
intake; avoid excess phosphorus and protein intake, especially with evidence of concurrent renal disease; and provide additional
taurine and carnitine, if myocardial failure is present. This patient’s calculated resting energy requirement (RER), based on the
current body weight of 12 kg, is approximately 430 kcal/day (1,806 kJ/day). However, the RER is probably higher because of the
patient’s increased heart and respiratory rates. The dog’s daily energy requirement (DER) would be 600 to 700 kcal/day (2,510
to 2,928 kJ/ day). Frequent monitoring of body condition helps guide appropriate adjustments to this energy calculation.
2. Because of the suspected association of carnitine and taurine deficiency with dilated cardiomyopathy in American cocker spaniel
dogs, supplementation with L-carnitine (1 g per os, three times daily) and taurine (500 mg per os, twice daily) was also begun.
In this case, the whole blood taurine and plasma carnitine concentrations were depressed, justifying use of these supplements. In
many cases of L-carnitine deficiency, the plasma carnitine concentration is “normal” (for dogs fed commercial dry foods),
although endomyocardial biopsy may disclose myocardial carnitine deficiency. The relationship between blood and myocardial
taurine concentrations is less well defined, but it seems prudent to supplement the food of American cocker spaniels with both
taurine and L-carnitine.